Forming apparatus



P. waml 3,29,159

FORMING APPARATUS PULSE SOU EC 1N VENTQQ @404 M40/ AT TOR NE Y6 Sheet L of 4 P- W'ILDl FORMING APPARATUS Filed June 27 1967 IN VEN TQR @404. Mzp/ ATTORNEY PULSE SOURC Feb. 25, 1969 P. WILD] FORMING APPARATUS Sheet 3 of 4 Filed June 27, 1967 L .i r/

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BY M? 3,429,159 FORMING APPARATUS Paul Wildi, San Diego, Calif., assignor, by mesne assignments, to Gulf General Atomic Incorporated, San Diego, Calif., a corporation of Delaware Filed June 27, 1967, Ser. No. 649,290 US. Cl. 72-56 10 Claims Int. Cl. B21d 26/14; B23p 17/00 ABSTRACT OF THE DISCLOSURE Apparatus for forming a plurality of conductive work pieces or portions thereof by energy acquired from a transient magnetic field. The apparatus comprises a conductive coil. which produces a transient magnetic field when current pulses are passed therethrough. The field is shaped by a field shaper means positioned adjacent to the coil which shaping means defines a plurality of apertures, each aperture being of a size for accommodating one of the work portions. Means are provided for placing selected ones of the apertures in operative condition.

This invention relates to forming apparatus and, more particularly, to apparatus for forming material by energy acquired from a transient magnetic field.

Apparatus has been developed for forming materials by employing transient magnetic fields of high intensity. An example of such apparatus is shown and described in the US. Patent No. 2,976,907, issued Mar. 28, 1961, :and assigned to the assignee of the present invention. In apparatus of this general type, an electrical current pulse of high amperage is passed through a conductive coil, thereby producing a transient magnetic field of high intensity. A conductive Work piece positioned in the transient magnetic field, has a current induced in it corresponding to the changing flux of the transient magnetic field. The induced current pulse interacts with the magnetic field to produce a force acting on the work piece. If the force is sufficiently strong, a deformation of the work piece results. The shape of the deformation is dependent upon the shape of the magnetic field and the position of the work piece relative to the field. Repeated pulses of current may be applied to the conductive coil, thus causing a series of forming impulses to be applied to the work piece.

Ordinarily, greater force concentration than can be obtained from a conductive coil alone is provided by employing a mangetic field shaper. One form of field shaper is that of a conductive body, such as a conductive plate having an aperture therein for accommodating the work piece. The area of the aperture is ordinarily smaller than the area enclosed by the coil. The field shaper is disposed relative to the coil such that the transient magnetic field produced by the coil induces a transient current in the field shaper which is concentrated on its inner surface around the aperture, and creates an intense field in the aperture. The flux density within the aperture and, therefore, the force on the work piece are dependent upon the shape of the inner surface of the field shaper at the aperture and upon the location of the inner surface relative to the work piece. For example, a tube can be constricted intermediate its ends through the use of a field shaper which includes an annular flange projecting inwardly from the inner surface of the field shaper to define a narrow throat within the aperture.

In certain manufacturing operations it is often desirable nited States Patent 3,4Z9,l59 Patented Feb. 25, 1969 to perform a sequence of forming operations on work pieces, or portions thereof, which are of difierent sizes. A separate coil and shaper combination can be provided for each size of work piece or work portion, however, such a construction may prove costly and of excessive size for certain applications.

It is an object of this invention to provide improved apparatus for forming a plurality of conductive work pieces or portions thereof.

Another object of the invention is the provision of a magnetic forming apparatus for forming a necked-down area of a work piece.

A further object of the invention is to provide improved magnetic forming apparatus which is low in cost and which is capable of rapidly performing a variety of sequential forming operations on work pieces or portions thereof of different sizes.

Another object is to provide magnetic forming apparatus using at least one coil which produces only a single magnetic field, and using field shaping means wherein the effective size of the aperture used with the coil for forming may be varied.

A more particular object of the invention is to provide improved magnetic forming apparatus using at least one coil and field shaping means adjacent thereto defining a plurality of apertures in which work pieces or portions thereof may be formed in response to energization of the coil.

Still another object is to provide magnetic forming apparatus of the type described in which the work pieces or portions thereof may be readily inserted in the apertures.

Other objects of the invention will become apparent to those skilled in the art from the following description taken in connection with the accompanying drawings wherein:

FIGURE 1 is a side elevational view, with part broken away, of forming apparatus constructed in accordance with the invention;

FIGURE 2 is a sectional view taken along the line 22 of FIGURE 1;

FIGURE 3 is an enlarged respective view of one type of device which may be formed in the apparatus of the invention;

FIGURE 4 is a side elevational view of another embodiment of the forming apparatus;

FIGURE 5 is a sectional view taken along the line 55 of FIGURE 4;

FIGURE 6 is a side diagrammatic view, with parts broken away, of a further embodiment of the forming apparatus and showing an alternative position thereof in phantom;

FIGURE 7 is a sectional view, taken along the line 77 of FIGURE 6;

FIGURE 8 is a side elevational view, with parts broken away, of a still further embodiment of the forming apparatus;

FIGURE 9 is a sectional view taken along the line 9-9 of FIGURE 8; and

FIGURE 10 is an enlarged sectional view taken along the line 1010 of FIGURE 8 and illustrating a plug and work piece used therein.

Very generally, the apparatus of the invention is utilized for forming a plurality of conductive work pieces or portions thereof (hereinafter referred to collectively as work portions). Briefly, the apparatus illustrated in FIGURES 1 and 2 comprises a conductive coil 11 for producing a transient magnetic field and field shaping means 13 and 15 positioned adjacent to the coil. The field shaping means define a plurality of apertures 17 and 19, each being of a size for accommodating one of the work portions to be formed. Means 21 are provided for placing selected ones of the field shaping means in an operative condition. Energizing means 23 is provided for supplying the coil 11 with one or more current pulses to thereby establish the transient magnetic field which forms the work portions positioned in the selected aperture.

Referring now more particularly to FIGURES l and 2, the magnetic forming apparatus illustrated therein includes the coil 11 which is a helically wound conductor. The coil 11 is insulated by suitable insulation 24 and the insulated coil is embedded in an annulus 25 of high strength conductive metal having a radially extending slot 26. The coil 11 produces a transient magnetic field when the same is selectively connected to the energizing means 23, which is a suitable pulse source such as a charged capacitor bank.

The transient magnetic field is shaped by the field shaping means 13 and 15 which comprise a pair of generally rectangular conductive plates of a high strength metal, such as beryllium copper, steel, etc., extending transversely of the axis of the coil 11 at opposite ends of the coil. The plate 13 defines the aperture 17 and the plate 15 defines an aperture 19. The surface of the plates 13 and 15 at the apertures are chamfered to provide a desired magnetic field strength and configuration for forming work portions disposed in the apertures. The aperture 17 is larger than the aperture 19 for accommodating a correspondingiy larger work portion.

Each of the plates 13 and 15 is separable at the respective apertures 17 and 19 along interfaces 27 and 28, respectively. This permits the separable parts of each plate to be moved away from each other to facilitate the insertion of a work portion in the associated aperture. In order that current flows around the apertures and produces a proper forming field, the plates do not actually contact each other at the interface on at least one side of the aperture. Contact may be avoided by a strip of insulation 29 attached to one interface. To facilitate movement of the separable parts of the plates 13 and 15, the plate 13 is supported between upper and lower tracks 30 and 31, respectively, and, similarly, the plate 15 is supported between upper and lower tracks 33 and 35, respectively. As will be observed from FIGURES 1 and 2, the plate 15 is shown having its two parts separated from each other. In this position, the aperture 19 is inoperative because of the excessive gap and because it is not properly aligned with the coil. The aperture 17 may be rendered inoperative by separating the separable parts of the plate 13. Thus, the apertures may be selectively rendered operative or inoperative in accordance with the relative position of the separable parts of the plates.

In the embodiment illustrated in FIGURES 1 and 2, the means 21 for placing the field shaping means in operative condition are pneumatic actuators connected to the separable parts of the plates 13 and 15 for moving same with respect to each other. As an alternative, one of the separable parts of each plate may be fixed with respect to the coil 11, and only one of the separable parts made movable with respect thereto.

Rectangular blocks 37 and 39 of high strength insulating material are provided on the opposite side of each of the field shaper plates 13 and 15 from the coil 11 to provide backup for the plates to prevent their being pushed away from the coil due to the force of the magnetic field produced thereby. Axial apertures 40 are provided in the blocks 37 and 39 to permit positioning of the work portions in the field shaping means 13 and 15. The blocks 37 and 39 are, in turn, encased by an annular channel shaped metallic casing 41 which provide structural support and at the same time limits stray magnetic fields outside of the apparatus. The casing 41 is, in turn,

4 fixedly attached to a machine frame (not shown) by suitable means (not shown).

The operation of the apparatus illustrated in FIGURES 1 and 2 will be described in connection with a specific application in which such apparatus is of advantage. It is to be understood, however, that the invention may be used for other applications, with or without modification. In FIGURE 3, a flexible mechanical joint between a yoke structure 43 and a coupling rod 45 is covered by a flexible rubber boot 47. Such a construction is sometimes utilized in vehicles, wherein the flexible rubber boot is used to retain lubricant at the flexible joint. The boot is secured by means of two rings 49 and 51 positioned a short distance in from the respective ends of the boot. The rings 49 and 51 may be tightened to the boot by the apparatus shown in FIGURES 1 and 2. The ring 49 is positioned between the two separable parts of the plate 13, and the plate closed such that the aperture 17 is in an operative condition accommodating the ring 49. A suitable transient magnetic field may then be produced by the coil 11 to magnetically form the ring 49 against the boot. The separable parts of the plate 13 may then be opened and the separable parts of the plate 15 brought together so that the aperture 19 encloses the ring 51. Once the ring 51 is positioned in the aperture 19, a transient magnetic field is produced by the coil 11 to form the ring 51 against the boot.

It will be appreciated that the handling of the assembly of FIGURE 3 in apparatus in accordance with FIG- URES l and 2 is considerably simplified over that which would be necessary in the event two separate coils for forming each of rings 49 and 51 were used. If sufiicient magnetic energy is available and the plates are properly spaced apart, both rings may be formed simultaneously with the separable parts of the plates 13 and 15 both closed so both apertures 17 and 19 encompass the respective rings. Although the apparatus has been described in connection with one coil 11, it is to be understood that two or more coils suitably connected and shaped to act as a single coil for producing a single magnetic field of appropriate configuration may also be used in connection with the two plates 13 and 15.

A forming apparatus of similar configuration to that of FIGURES 1 and 2 is illustrated in FIGURES 4 and 5. Parts similar to those in FIGURES 1 and 2 are indicated with the same reference numeral and the subscrip a. In this embodiment diiferent sized work portions are formed in the same plane in the forming apparatus. More particularly, as illustrated, two coils 53 and 55 of spiral configuration and substantially fiat cross section are embedded, respectively, in two annular blocks 57 and 59 of high strength insulation, such as fiber glass. As illustrated, the pulse source 23a feeds the two coils in series, but, for certain applications the coils may be coupled in parallel. The annular blocks 57 and 59 are spaced from each other and are supported and backed by rectangular plates 61 and 63, respectively, of a high strength material such as steel. The plates 61 and 63 are, in turn, fixedly supported by a machine frame (not shown). Each plate has therein a central opening 64 large enough to accommodate insertion of work portions. The space between the two plates 61 and 63 is occupied in part by four spacers 65 formed of a high strength metal, one being positioned at each corner. The plates 61 and 63 are fastened to the spacers 65 by suitable means such as bolts (not shown).

The field shaping means 13a and 15a comprises two field shaper plates 67 and 69 which are positioned in coplanar relationship in the space between the blocks 57 and 59. The plates 67 and 69 define apertures 71 and 73, respectively, and are separable at the apertures which they define along interfaces 75 and 77, respectively. Actual contact between the separable parts of the plates is avoided by insulating strips 78 attached to the interfaces 75 and 77. The separable parts of the plates 67 and 69 are guided by the insulating blocks 57 and 59 and by tracks 70 provided on the spacers 65. As was the case in the previously described embodiment, the apertures 71 and 73 may be made of different sizes for accommodating work portions of different sizes.

It will be appreciated that the separable parts of the plates 67 and 69 are movable with respect to each other in different directions such that the plates may be alternately closed to render the respective apertures 71 and 73 in an operative condition. More particularly, the interfaces 75 and 77 are mutually perpendicular as are the directions in which the separable parts are moved relative to each. Thus, with one plate having its parts sufi'iciently separated, the other may be closed to render its aperture in an operative condition.

By combining the features of the embodiment of FIG- URES 1 and 2 with the features of the embodiment of FIGURES 4 and 5, an apparatus may be provided which includes a coil, such as the coil 11 of FIGURE 1, disposed between two pairs of separable field shaper plates, each pair being as illustrated in FIGURES 4 and 5. Such a construction is capable of handling work portions of up to four different sizes, and capable of simultaneously forming two work portions if sufficient energy is provided.

Referring now to FIGURES 6 and 7 an embodiment of of the forming apparatus is illustrated, which is similar to FIGURES 4 and 5 except that a single field shaper 79 is provided which includes a plurality of apertures 81, 83 and 85. Parts similar to those in FIGURES 4 and 5 are indicated with the same reference numeral and the subscript b.

The field shaper plate 79 is supported in an upper track 87 and a lower track 89 on a rectangular frame structure 91 which also supports the pneumatic actuators 21b. The plate 79 defines the three vertically spaced apertures 81, 83, and 85 of different sizes, and is separable into two parts at the apertures along a vertically extending interface 93.

In order to select an aperture for operation with the coils 53b and 55b, an actuator 96 is attached to the frame structure 91 which is guided for vertical movement by opposed vertically extending tracks 97 and 98 attached to the spacers 65b disposed between and at opposed sides of the plates 61b and 63b. Movement of the frame structure 91 effects vertical movement of the field shaper plate 79, thereby permitting a selected aperture to be axially aligned with the coils 53b and 55b for operation therewith, depending upon the effective aperture size desired. The actuator 96 may be a hydraulic device, a jack screw, a rack and pinion, or any other suitable device.

Referring now to FIGURES 8, 9 and 10, a forming apparatus is shown which is similar to that shown in FIGURES 4 and 5 except that a single field shaper plate 99 is provided which contains two horizontally spaced apertures 100 and 101 of different sizes. Parts similar to those shown in FIGURES 4 and 5 are indicated with the same reference numeral and the subscript c. As may be seen in FIGURE 9, the coils 53c and 550 are oval for the purpose of exposing the two apertures 100 and 101 in the field shaper plate 99. The plate 99 is separable at both of the apertures along an interface 103 and the parts are guided for vertical movement by opposed tracks 104 attached to the spacer 656. An insulating layer 105 attached to one face of the interface prevents the two parts from contacting each other.

In order to insure that the magnetic forces will be of sufiicient magnitude in the aperture being used for forming, the aperture which is not being used for forming is filled with a conductive plug 107, as shown in FIGURE 10. A similar plug (not shown) may be provided for the aperture 100, and when positioned in the aperture 100 renders that aperture inoperative. In the latter case, of course, the plug 107 is removed to permit insertion of a work portion in the aperture 101.

It may therefore be seen that the invention provides an improved forming apparatus. The apparatus is particularly adaptable to the forming of a plurality of conductive work pieces or portions thereof by utilizing a coil or coils producing a single magnetic field and a field shaper or field shapers in which the effective aperture size may be selectively varied. The forming device of the invention is capable of performing a variety of sequential forming operations on work portions of different sizes. The Work portions are readily inserted into the apparatus and removed therefrom through relative movement of separable parts of the shaper or shapers.

Various embodiments of the invention other than those shown and described herein will become apparent to those skilled in the art from the foregoing description and accompanying drawings. Such other embodiments, and modifications thereof, are intended to fall within the scope of the appended claims.

What is claimed is:

1. Apparatus for forming a plurality of conductive work portions, comprising, at least one conductive coil for producing a magnetic field, field shaping means positioned adjacent to said coil and defining a plurality of apertures, each aperture being of a size for accommodating one of the work portions, means for placing selected ones of said apertures in an operative condition, and means for energizing said coil for forming work portions in those of said apertures in the operative condition.

2. Apparatus in accordance with claim 1 wherein said field shaping means comprise at least one conductive plate having at least one of the apertures therein, said plate being separable at said aperture therein to facilitate placement of a work portion in said aperture.

3. Apparatus in accordance with claim 1 wherein said field shaping means comprise a pair of conductive plates, each having an aperture therein and being separable at said aperture therein into at least two relatively displaceable parts, and wherein said placing means comprise means for effecting relative movement of the separable parts of each of said plates between a separated relationship and an adjacent relationship wherein said aperture defined thereby is in the operative condition.

4. Apparatus in accordance with claim 3 wherein said plates extend transversely of the axis of said coil at op posite ends thereof, and wherein said apertures in said plates are substantially aligned with the axis of said coil in the operative condition.

5. Apparatus in accordance with claim 3 wherein said plates are coplanar and wherein said separable parts of said plates are movable in different directions so as to permit the separable parts of one plate to be brought together with the separable parts of the other plate separated.

6. Apparatus in accordance with claim 5 wherein each of said plates is separable into two parts and wherein said different directions are mutually perpendicular.

7. Apparatus in accordance with claim 1 wherein said field shaping means comprise two plates disposed transversely of the axis of said coil, each plate being at a respective end of said coil, each plate having an aperture therein and being separable at said aperture therein into at least two relatively displaceable parts, said separable parts of said plates being movable in different directions so as to permit the separable parts of one plate to be brought together with the separable parts of the other plate separated, and wherein said placing means comprise means for effecting relative movement of the separable parts of each of said plates between a separated relationship and an adjacent relationship wherein said aperture defined thereby is in the operative condition.

8. Apparatus in accordance with claim 1 wherein said field shaping means comprise a single plate having a plurality of apertures therein.

9. Apparatus in accordance with claim 8 wherein Said movable means comprise means for moving said plate with respect to said coil for selectively positioning said apertures to have their axes aligned with the axis of said coil.

10. Apparatus in accordance with claim 8 wherein said apertures are positioned to have their axes both within the perimeter of said coil, and wherein said placing means comprise means for magnetically blocking selected apertures.

8 References Cited UNITED STATES PATENTS 2,976,907 3/1961 Harvey et al. 7256 3,108,325 10/1963 Harvey et al. 72-56 5 3,252,313 5/1966 Eilers et a1 7256 3,347,074 10/1967 Eilers et al. 7256 RICHARD J. HERBST, Primary Examiner.

US. Cl. X.R. 

